1. Field of the Invention
The invention relates to a spinning method and a spinning apparatus suitable to be applied when integrally forming a member having a three-dimensionally complex cylindrical shape, such as an exhaust pipe of a vehicle for example, from a cylindrical work.
2. Description of Related Art
Japanese Patent Application Publication No. 2001-25826 (JP 2001-25826 A), for example, describes one such spinning method that reduces the diameter of a processed portion of a cylindrical work, by pressing approximately two to four rollers against an outer peripheral surface of the processed portion of the work while revolving the rollers, while a cylindrical work is being supported by a chuck or a clamping device.
However, with this kind of spinning method, processing is performed by pressing the rollers from the outside of the work toward the inside of the work (i.e., toward the axis of the work). Therefore, normally, forming beyond the outer shape of the work (i.e., processing to form the axis of the work in a given direction without being limited to the area within the outer shape (the cylindrical shape) of the work), e.g., an offsetting process, is unable to be performed on the work.